Lawnmower sharpener



5 Sheets-Sheet 2 Filed June 14, 1954 II I T lllllllflill /NVE NTOR. CH9rues L. Tue/v0? BY HAS HTTOPNEYG. HflRRIS, Mic/4, FOSTER & HHRR/S toeither raise or lower the side 2,780,034 Patented Feb. 5, 1957 LAWNMOWERSHARPENER Charles L. Turner, Pocatello, Idaho,

assignor of one-half to Marjory C. Turner,

Lawnmowers of the type illustrated and described herein are very common,millions of them being in use in the United States. These lawnmowersconsist of two wheels between which there is mounted a reel which isgeared to these wheels and rotated thereby. Mounted uponthe reel are aplurality of curved reel knives, each of which is designed to contact abed knife mounted between the two wheels in such a manner as to cutgrass. The knives of such lawnmowers become dull in use and mustperiodically be sharpened. Such sharpening is preferably done by meansof a grinding wheel which sharpens the blades of a lawnmower mounted ina lawnmower sharpener. It is an object of the present invention toprovide an improved form of a lawnmower sharpener which is designed tobe used in sharpening the reel knives of a lawnmower.

My invention may be briefly summarized as embodying a frame and novelmeans for supporting a lawnmower in said frame so that a power-drivengrinding wheel may be accurately applied to the reel knives of themower. More specifically, my invention is defined by the claims forminga part of the following specification. Further details of the inventionwill be apparent from the remainder of this specification and theaccompanying drawings, in which:

Fig. l is an isometric view of a lawnmower sharpener of the presentinvention;

Fig. 2 is a partially cross-sectional view taken generally along line 22of Fig. 1;

Fig. 3 is a partial top view taken in the direction of the arrow 3 inFig. 1;

Fig. 4 is a partially sectional view taken at line 4-4 of Fig. 3;

Fig. 5 is a of Fig. 2;

Fig. 6 is an enlarged view showing guide means employed with theinvention, this view being taken inthe direction of the arrow 6 in Fig.5; and

Fig. 7 is a partially sectional view taken along the line 7--7 of Fig.5.

In Fig. 1 there is shown partially sectional view taken at line 5-5 alawnmower sharpener 10 including a machine frame 11 serving as a basefor the sharpener. This machine frame 11 consists of legs 12, 14, 15 and16, crossbraces 17, top supports 18, and a generally flat top section19.

Mounted upon the machine frame 11 is what is gen erally designated aroller support frame 21. This latter frame is secured to the machineframe 11 by means of bolts 22 attaching side braces 23 of the rollersupport frame 21 to angle members 24 fastened to the top 19. These sidebraces 23 each carry threaded bearings 25 through which there projectthreaded cranks 26 having lower support surfaces 27 which are adapted tobear against the top 19 of the machine frame 11. As will be readilyapparent, these cranks 26 may be rotated so as braces 23 about the bolts22. Each of the side braces 23 also has an upstanding end support 23mounted on the end 29 of the side braces 23 remote from the bolt 22.These upstanding end supports 28 are provided with several generallyaligned V- shaped supports 30 which are adapted to hold an angle ironbrace 31 in an inverted position with the apex 31 or" this angle ironbrace in a generally downward position, as indicated in Fig. 2 of thedrawings. This angle brace 31 is adapted to carry support braces 32consisting of a lower member 33 fitting within the angle brace 31, andupstanding members 34 having upper V-shaped notches 35 which are adaptedto hold the roller of a lawnmower above the angle brace 31 when the sizeof the lawnmower makes this desirable. The support braces 32 also carryclamping flanges 36 attached to the lower member 33. The clampingflanges 36 each carry a threaded bearing 37 and a threaded crank 38which is adapted to be rotated within the bearing 37 so as to hold thesupport brace 32 at any desired location along the angle brace 31.Preferably, these support braces 32 are positioned substantially asshown in Figs. 1 and 2 of the drawings so as to hold the ends 41 of aroller 42 attached to a lawnmower 43.

The lawnmower 43 includes wheels 44, a reel 45 mounted upon a shaft 46extending between the wheels 44, a bed knife 47 carried upon anappropriate conventional carrying member 48 secured between the twowheels 44, and a top tie rod 49. The reel 45 includes hubs 59 carryingreel knives 51 (Fig. 2.). The roller 42 is connected to the rest of themower 43 by means of supporting arms 52.

The lawnmower 43 is held in position with the roller 42 in the locationindicated by means of a balancing assembly 56 which includes a pipe 57rotatably held within U-shaped brackets 58 mounted upon the legs 12 and14- of the machine frame 11. jacent its center an extended rod 59 towhich there is secured a second rod 60 by means of a bearing assembly 61including cranks 62 designed to secure the rods 59 and 60 to oneanother. The rod 60 is attached to at least one Z-shaped bracket 63(Fig. 2) containing a bottom wall 64 attached to the rod 60, anupstanding wall 65 projecting generally parallel to the rod 60, and atop wall 66 which is substantially perpendicular to the wall 65 andparallel to the wall 64. The Z-shaped bracket 63 is adapted to bepositioned over the tie rod 49 of the lawnmower 43 substantially asshown with the rods 59 and 60 being adjusted as necessary.

As illustrated in Fig. 2 of the drawings, when the balancing assembly 56is used for the purpose described, the tie rod 49 of the lawnmower 43 isheld between the walls 64 and 65 of the Z-shaped bracket 63. If desired,the tie rod could be held between the walls 66 and 65 of this samebracket by rotating the rod 60. The precise shape of the bracket 63 isdesigned so that either side of this bracket can be utilized for holdingthe tie rod 49. In order to prevent movement of the lawnmower 43 duringoperation of the lawnmower sharpener 10, a link 67 is attached to therod 60 adjacent the Z-shaped bracket 63, and this link in turn isconnected to a spring 68 which is fastened to the cross braces 17 asindicated in Fig. 1 of the drawings. In effect, the arrangement createdin the balancing assembly 56 is one in which the lawnmower 43 is held inwhat may be termed an overcenter locked position in which rotation ofthe lawnmower 43 towards the pipe 57 is prevented because of the fixedposition of the rod 60.

Immediately above the lawnmower 43 there is placed a grinder supportframe 71 including upstanding supports 72 mounted upon the top supports18 by means of bolts 73 so as to be rotatable about these bolts withrespect to the machine frame 11. Each of the supports 72 is providedwith a crank bracket 74 carrying a threaded crank 75, one end of whichis secured rotatably within a bushing 76. The bushings 76 are mountedupon the legs 12 and 14 as indicated in Fig. l of the drawings.

The pipe 57 carries ad- By virtue of this construction, it is possibleto adjust the location of the supports 72 as desired.

The ends '77 of these supports 72 are formed in the shape of curvednotches which are intended to carry 'cylindricalend,sections 78 (Figs. 3and 4) of a cylindrical' support 79 projecting between the supports 72above the lawnmower 43 and the other items previously described. As isapparent from Figs. 3 and 4 of the drawings, the support 79 includes endflanges serving to retain the end sections 78 within the ends 77. Asshown in the drawings, these end sections 715 are preferably of smallerdiameter than the support 79. The cylindrical support 79 is rotatable inthe curved notches in the' ends 77 of the supports 72. This permits thesupport'79 to be rotated during the lifetime of the machine, therebydistributing the wear on the support around its entire circumference.

The support 79 is adapted to carry a grinder assembly 85 includingrollers 86 carried by a frame 87 projecting generally'below the support79. This frame 87 holds an attached electric motor 88, a motor controlswitch 89, a grinding wheel 90, and a grinding guide 91. As is apparentfrom Figs. 1 and 2 of the drawings, a belt 92 mounted on pulleys 93attached to the motor 88 and the grinding wheel 90 is used to rotatethis grinding wheel. As best seen in Figs. 2, and 7, a guide frame 94'is secured to the frame 37 so as to be positioned on the side of thegrinding wheel 90 remote from the frame 87. This frame 94 includes aslot 95 and parallel guide ridges 96. In use a guide 97 having a flatside 98 is held in position between these ridges against the frame 94 bymeans of a bolt 99 projecting through the slot 95. The guide 97 includesa curved bottom 101 leading to a projecting tongue 102. This tongue 102is adapted to be adjusted soar; to bear against a reel knife 51 whenusing the. sharpener 10.

A bushing 105 forming, together with the various attached members.indicated below, the grinding guide 91, is secured to the frame 87 belowthe grinding wheel 90; this bushing is provided with an opening 106carrying a threadedshaft 107, the end of which adjacent to the lawnmower43 is provided with a hook follower 108 and the other end of which isprovided with a handle 109. The shaft 107 is provided with a flat face110 against which a block 111 is normally held during operation of thedevice by means'of a leaf spring 112, as is apparent from Fig. 6 of thedrawings. This leaf spring is secured to the bushing 105 and to theblock 111 by means of screws 114. The shaft 107 carries a threadedfollower'115 positioned on the side of the bushing 105 remote from theblock 111. This follower 115 includes a handle 116, a depressed centerportion 117, and a flange 118 which is located immediately adjacent tothe bushing 105. A hook 119 secured to the bushing 105 engages thisflange 118, preventing movement of the follower 115 away from thebushing as this follower 115 is turned. Unintentional rotation of thefollower 115 is prevented by means of a spring 120 which is attached tothe bushing by screws 114 so as to bear against the flange 118.

The operation of the lawnmower sharpening machine is essentially verysimple. In using this device, the lawnmower 43 is moved into position bymeans of a hoist 125 of essentially conventional design mounted on anupward extension 126 of the leg 14. The various component parts of themachine 10 are adjusted substantially as illustrated in the drawings inorder to receive this lawnmower, and to hold it so that the grindingwheel 90 and the grinding guide 91 are immediately adjacent the reel 45and the bed knife 47. positions of these parts, adjustment of thevarious cranks, etc. is, of course, necessary.

After the mower has been located in this manner, the grinder assembly 85is moved upon the support 79 to adacent a stop 127, and the switch 89isactuated, turn- In order to obtain the ing on the motor 83 causing thegrinding wheel 90 to rotate. The grinding assembly 8d is manually movedfrom adjacent the adjustable stop 127 to adjacent another adjustablestop 128. The grinder assembly is pulled across the reel knives of themower 43 by a cord 130 which is attached to the frame 87 and runs over apulley 131, a weight 129 providing a tension force in the cord 13%). Theforce applied to the frame 8'7 by the cord 130 may be adjusted byvarying the weight 129 so that the grinding of the reel knives 51proceeds at a pace corresponding to the amount of grinding needed forthese knives.

The support member 79 is adjusted with respect to the reel knives 51 sothat theforce of gravity acting on the grinder assembly tends to movethe grinder assembly away from the reel knives. The guide assembly 91maintains the grinder wheel 91} in the desired position by means of thehook end 108 which rides on the top surface of the bed knife 47. By thisarrangement, the clearance between the bed knife and the ground reelknife is maintained constant regardless of the variations in the contourof the bed knife. The relationship of the cylindrical support member 79and the reel knives 51 may be adjusted so that the pressure exerted bythe grinder wheel on the reel knives is at an optimum value forefficient blade sharpening. It is essential that this pressure is nottoo great so that the cord 13% and weight 129 can traverse the grinderalong the knife. The grinder wheel rotates clockwise, as seen in Fig. 2,applying a counterclockwise torque to the reel 45, causing the reelknife to rest the tongue 1492.

After a particular reel knife 51 has been ground, the handle 109 isrotated, disengaging the hook 108 from the bed knife 47, and the grinderassembly 85 is pulled away from the lawnmower 43 and brought backadjacent the stop 127 where the handle 109 is rotated, locking anotherreel knife 51 in contact with the grinder wheel 90 and again hooking thehook 108 over the bed knife 47. The grinder assembly 85 is broughtagainst the stop 128 by a weight 129 pulling on a cord 130 attaching theframe 87 to the upstanding support 72. The cord 130 goes over pulleys131 and 132 substantially as shown. The grinding step indicated is thenrepeated.

Those skilled in the art will realize that the machine herein describedis exceedingly efiicient for the purpose intended and may be readilymanufactured with a minimum of difficulty. Because of the fact that allthe moving parts with the machine are located in what may be generallytermed an inaccessible position, it may be located in a crowded shopwhere customers are apt to come in contact with the machine whiletransacting business.

Those skilled in the art will realize that the herein describedinvention is capable of modification within the scope of the instantdisclosure. Such modifications are to be considered as part of theinventive concept insofar as they are defined by the appended claims.

I claim as my invention:

1. A new and improved lawnmower sharpener, which comprises: a machineframe serving as a base for said sharpener; a roller support frameattached to said machine frame, said roller support frame being adaptedto support a roller of a lawnmower; a balancing assembly attached tosaid machine frame for engaging part of a lawnmower and holding saidlawnmower in a fixed position with respect to said roller support frameand said machine frame; a grinder support frame secured to said machineframe, said grinder support frame projecting above said roller supportframe and said balancing assembly, said grinder support frame includingan upper portion positionable substantially vertically above a lawnmowerplaced upon said roller support frame, the upper portion of said grindersupport frame being movable, in an approximately horizontal path,relative to said roller support frame and said balancing assembly; agrinder assembly including a grinder Wheel and a motor and guide meansfor engaging a lawnmower and guiding said grinder wheel with respect tosaid lawnmower and said grinder support frame, said grinder assemblybeing movably attached to said grinder support frame, said guide meansrestraining said grinder assembly from swinging away from a lawnmowerengaged by said guide means; and means for moving said grinder assemblywith respect to a lawnmower positioned upon said roller support frame.

2. A lawnmower sharpener as defined in claim 1, wherein said grindersupport frame includes a cylindrical support member located generallyparallel to said roller support frame above said roller support frameand said balancing assembly a suflicient distance so as to be above alawnmower placed upon said roller support frame, said grinder assemblybeing capable of moving about the axis of said cylindrical supportmember and along the length of said cylindrical support member, saidgrinder assembly being carried by said cylindrical support member.

3. In a lawnmower sharpener, the combination of: a base; a rollersupport mounted on said base, said roller support being movable relativeto said base in a substantially vertical plane, said roller supportbeing adapted to support a roller of a lawnmower; overcenter lockingmeans rotatably mounted on said base, said overcenter locking meansincluding angle means for engaging part of a lawnmower and spring meanscoupling said angle means to said base, said spring means urging saidangle means toward said roller support when a lawnmower is positionedtherebetween; a grinder support frame mounted on said base and includinga support member positioned above said roller support and saidovercenter locking means, said support member being movable in anapproximately horizontal path relative to said roller support; and agrinder assembly movably attached to and dependent from said supportmember, said grinder assembly including a grinder wheel and guide means,said guide means engaging the bed knife of a lawnmower mounted on saidroller support and exerting a force on said grinder assembly contra tothe force of gravity thereon, said guide means force urging said grinderwheel toward the lawnmower, said approximately horizontal movement ofsaid support member varying said guide means force.

4. A new and improved lawnmower sharpener, which comprises: a machineframe serving as a base for said sharpener; a roller support frameattached to said machine frame, said roller support frame being adaptedto support a roller of a lawnmower; a balancing assembly having asupport member rotatably carried by said machine frame, adjustablespacer rod means attached to said support member, angle means attachedto said adjustable spacer rod means, and spring means connecting saidangle means with said machine frame, said spring means normally tendingto rotate said angle means toward said roller support frame so as toforce a lawn mower engaged by said angle means against said rollersupport frame; a grinder support frame secured to said machine frame,said grinder support frame projecting above said roller support frameand said balancing assembly a sufiicient distance so as to be above alawnmower placed upon said roller support frame, the upper portion ofsaid grinder support frame being movable, in an approximately horizontalpath, relative to said roller support frame and said balancing assembly;a grinder assembly including a grinder wheel, a motor and guide meansfor engaging a lawnmower and guiding said grinder wheel with respect tosaid lawnmower, said grinder assembly being movably attached to saidgrinder support frame, said guide means restraining said grinderassembly from swinging away from a lawnmower engaged by said guidemeans; and means for moving said grinder assembly with respect to alawnmower positioned upon said roller support frame.

References Cited in the file of this patent UNITED STATES PATENTS556,868 Schareman Mar. 24, 1896 963,964 Warner Apr. 26, 1910 1,043,948Mandley Nov. 12, 1912 1,389,588 Klay Sept. 6, 1921 2,180,911 Rogers Nov.21, 1939 2,281,055 Smith #1 Apr. 28, 1942 2,441,045 Toepfer May 4, 19482,456,827 Greeley Dec. 21, 1948 2,493,619 Comstock Jan. 3, 19502,530,479 Pater et al. Nov. 21, 1950

